Real time brachytherapy spatial registration and visualization system

ABSTRACT

A method and system for monitoring loading of radiation into an insertion device for use in a radiation therapy treatment to determine whether the treatment will be in agreement with a radiation therapy plan. In a preferred embodiment, optical sensors and radiation sensors are used to monitor loading of radioactive seeds and spacers into a needle as part of a prostate brachytherapy treatment.

CROSS-REFERENCE AND PRIORITY CLAIMS TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.09/573,415 filed on May 18, 2000, now U.S. Pat. No. 6,512,942, which isa continuation of U.S. application Ser. No. 09/087,453 filed on May 29,1998, now U.S. Pat. No. 6,129,670, which is a continuation-in-part ofU.S. application Ser. No. 08/977,362 filed on Nov. 24, 1997, now U.S.Pat. No. 6,256,529.

CROSS-REFERENCE TO COMPUTER PROGRAM LISTING ON COMPACT DISC

This patent application includes a Computer Program Appendix on compactdisc.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention is directed in general to an improved method andapparatus for carrying out minimally invasive treatments of the humanbody by virtual reality visualization of the treatment area. Moreparticularly the invention is concerned with use of an apparatus andmethod for providing real time images of a human anatomy undergoingtreatment along with rapid radiation seed therapy planning and rapidperformance of therapy including an automatic seed loading methodologywhich enhances therapeutic treatment with greatly improved efficiencyboth in terms of time and resources.

New minimally invasive surgical procedures are most often opticallyguided, but such optical guidance methods do not permit visualizationand guidance of instruments or probes within (inside) the target tissueor organ. Incorporation of real-time three-dimensional visualizationinside diseased tissues would provide accurate guidance of therapy.Open-magnet MRI is used to visualize some procedures such as thermaltherapy and brain biopsies. However, the method is expensive, not trulyreal-time, and is limited in application.

Numerous conventional treatment methods involve attempts to provide atargeted dosage of radiation or chemicals to the organ, and suchtreatments are often based on general anatomical assumptions of size andlocation. These methods suffer from inaccuracy of localizing the targetfor any one particular individual and potential real time changes ofrelative orientation and position of target tissue, normal tissue, andradiation therapy devices.

It is instructive in explaining the invention to consider one specifictype of exemplary condition, adenocarcinoma of the male prostate whichis the most commonly diagnosed cancer in the male population of theUnited States. At present, 254,000 new cases of prostate cancer werediagnosed in 1995 and 317,000 in 1996. In the 1960s, a method ofimplanting radioactive gold or iodine seeds was developed. With thisapproach, the radioactive material is permanently placed into theprostate via a retropubic approach during laparotomy when diagnosticlymphadenectomy was also being performed. A high dose of radiation isdelivered to the prostate as the radioactive seeds decay. In severalreports, the five year disease free survival (“local control”) obtainedby this method was compared to similarly staged patients treated with anexternal radiation beam. In view of this, gold was replaced by I¹²⁵implantation for safety of personnel doing implantation. Except forearly stage prostate cancer (T2a tumors), inferior rates of localcontrol are reported with “free hand” 125-Iodine implantation. There wassignificant dose inhomogeneity due to the nonuniformity of seedplacement, leading to underdosing of portions of the prostate gland andsignificant complications due to overdosing of adjacent healthy tissuestructures. The poor results for local control and normal tissuecomplication were attributed to the doctor's inability to visualize andhence control where the radioactive seeds were actually being depositedinside the patient.

Recently, transrectal ultrasonography (“TRUS”) has been used tovisualize 125-Iodine seed placement during transperineal implantation.The early reported rates of serious late complications is higher thanexternal beam therapy. Even with this technique, significantimprecisions in seed placement are observed. Due to the proximity of theprostate to the rectum and bladder, incorrect seed placement may lead toserious overdosing of these structures and late complications.

The recent transrectal ultrasound guided transperineal implant techniquehas been developed which is in use. That procedure is described in threesteps: (1) the initial volumetric assessment of the prostate glandperformed using ultrasound, (2) development of a radiation therapy“pre-plan,” and (3) performing the actual intraoperative implant. Thepurpose of the initial volumetric assessment prior to the pre-plan orimplantation is to obtain a quantitative understanding of the size ofthe prostate, which is then used to determine the total activity anddistribution of radioactivity which is to be implanted into theprostate. To perform the assessment, an ultrasound probe is physicallyattached to a template. The template is a plastic rectangle whichcontains an array of holes separated at predefined intervals, usually 5mm. The template system serves two purposes: (1) to fix the ultrasoundprobe, and hence the imaging plane to the reference frame of thecatheter and seed positions, and (2) to guide the catheters into theprostate volume. More specifically, the template system serves as areference frame for spatial quantities which are required for thedescription of the implant procedure. Using transrectal ultrasound, anumber of serial ultrasound images are obtained at 5-mm intervals, andthe prostate is outlined on each image. The images are taken so that theentire prostate gland is covered. This results in a stack oftwo-dimensional outlines, or contours, which, taken together, outlinethe entire three-dimensional prostate volume. From this volume, thequantitative volume of the prostate is calculated.

Once the three-dimensional contour data has been obtained for theprostate volume, a radiation therapy plan which describes the positionsof the radioactive seeds within the prostate is developed. This planattempts to optimize the dose to the prostate, minimize the dose tosurrounding healthy tissue, and minimize dose inhomogeneity. Thepositions of the radioactive seeds are constrained to fall within thecatheter tracks, since the seeds are placed within the prostatetransperineally via these catheters. The result of the pre-plandescribes the positions and strengths of the radioactive seeds withinthe catheter which optimizes the dose to the prostate.

Intraoperatively, the TRUS probe is inserted, and the template ismounted against the perineum. As previously described, the template is aplastic rectangle which contains an array of holes separated at fixedintervals. These holes act as guides for the catheters. The TRUS probeis inserted into the rectum and placed so that the image corresponds tothe prostate base (the maximum depth). Two or three catheters areinserted into the tissue surrounding the prostate or in the periphery ofthe prostate to immobilize the gland. These catheters contain noradioactive seeds. This image serves as a spatial reference for allfurther images and seed positions within the prostate. Subsequently,catheters are inserted into the gland based on the pre-plan through thetemplate. The ultrasound probe is positioned each time so that thecatheter, and hence seeds, which are inserted into the prostate arevisible on the ultrasound image. If the placement of the catheter withinthe prostate is not according to the pre-plan, the catheter is thenwithdrawn and reinserted until the catheter is correctly placed. This isa time-consuming process; and it is very difficult to achieve optimalplacement. Invariably, the catheters deflect angularly as they areinserted, and their positions are difficult to determine bytwo-dimensional ultrasound. This is due to the fact that thevisualization process is a two-dimensional process while the actualimplant procedure is three-dimensional. Once all the seeds are in place,another series of two-dimensional images are obtained to quantify thefinal, resultant dose distribution delivered to the patient. In someinstances, a pair of orthogonal fluoroscopic images are also obtained todetermine the final seed placements. This procedure is usually performeda few weeks post implant.

These above described prior art systems suffer from inherent inaccuracy,the inability to correct the positioning of the radioactive seedswithout repeated withdrawal and reinsertion of seeds into the prostateand are not real time manipulations of the therapeutic medium. Further,the overall positioning of the template and patient may be differentduring treatment compared to the assessment phase. Consequently, thecatheter position and seed position may be at an undesired positionrelative to the presumed assessment phase location.

It is therefore an object of the invention to provide an improved systemand method for invasive treatment of the human body.

It is another object of the invention to provide a novel system andmethod for real time and/or near real time, three-dimensionalvisualization of a human organ undergoing invasive treatment.

It is also an object of the present invention to provide a more preciseand accurate implant placement for radiation therapy, thermal therapy,and surgical ablation.

It is also an object of the invention to provide an improved system andmethod for generating a three-dimensional image data set of a humanorgan for a treatment protocol using a real-time ultrasound imagingsystem with spatial landmarks to relate the image data set to presenttime, invasive treatment devices.

It is a further object of the invention to provide a novel system andmethod for spatial registration of two-dimensional and three-dimensionalimages of a human organ, such as the human prostate, with the actuallocation of the organ in the body.

It is an additional object of the invention to provide an improvedmethod and system for three-dimensional virtual imaging of the maleprostate gland and overlaid virtual imaging of devices being insertedinto the prostate for deposition of radioactive seeds for cancertherapy.

It is yet a further object of the invention to provide an automatedmethod and system for loading of radioactive therapeutic treatment seedsbased on a clinical plan enabling rapid treatment based on substantiallyreal time pre-planning using rapid patient organ evaluation.

These and other objects and advantages of the invention will be readilyapparent from the following description of the preferred embodimentsthereof, taken in conjunction with the accompanying drawings describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block diagram of an embodiment of the inventionand FIG. 1B shows an alternate embodiment for a three-dimensional probe;

FIG. 2 illustrates an ultrasound guided implant system;

FIG. 3A illustrates patient setup for a radioactive implant procedure;FIG. 3B illustrates an anatomical prostate phantom used for testing andplanning; and FIG. 3C illustrates in detail a probe holder/stepperassembly shown partly in FIG. 3A;

FIG. 4A illustrates a front schematic view of a brachytherapy phantomand FIG. 4B a side schematic view of the brachytherapy phantom;

FIG. 5A illustrates reconstruction of standard orthogonal image planesfrom a three-dimensional image stack and FIG. 5B the reconstruction ofoblique image planes from a three-dimensional image stack;

FIG. 6 illustrates the viewing geometry for a three-dimensionaltranslucent reconstruction of an image;

FIG. 7A illustrates translucent images of a human prostate for fourdifferent viewing angles and FIG. 7B illustrates translucent images of aphantom organ for six different viewing angles;

FIG. 8 illustrates a time sequenced image of the prostate organ in FIG.7A showing approach of a catheter containing a radioactive seed,deposition of the seed and withdrawal of the catheter leaving the seed;

FIG. 9 illustrates isodose distributions of radiation from a singleradioactive seed;

FIG. 10 illustrates a flow chart of software routine for processingimaging data for visualization;

FIG. 11 illustrates a virtual reality head mounted display;

FIGS. 12A–12M illustrate flow diagrams of software module operativeconnections;

FIG. 13A illustrates a perspective view of a stepper assembly with theprobe in position and FIG. 13B illustrates a perspective view of theprobe stepper along with a probe stabilization system; and

FIG. 14 illustrates a redundant monitoring and automatic loading systemfor radioactive seeds and inert spacers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A system 10 constructed in accordance with an example of the inventionis illustrated generally in FIG. 1A. A three-dimensional probe 12accumulates image data from a treatment region or organ of a patient,image data is processed using a three-dimensional imaging card 14. Theprobe 12 preferably is an ultrasound device but can be any other rapidimaging technology, such as rapid CT or MR. A conventional personalcomputer 16 having a monitor can be used to operate on the image datafrom the imaging card 14 using conventional software and hardware toolsto be described in more detail hereinafter. Radioactive seeds 18 areprovided for insertion using any one of a variety of conventional meansfor inserting devices or articles into the human body, such as insertiondevices 19, which may be either needles or stiff catheters. Thethree-dimensional ultrasound probe 12, therefore, provides an imagesignal to the computer 16 and a virtual reality interface card 13coupled to the imaging card 14 which enables a user to visualize atranslucent image of the patient organ and real time interaction of anyone of a variety of treatment devices, such as the implant needles 19 ora Foley catheter 20, and one of the seeds 18 within the organ. Computersoftware can be utilized in a conventional manner to visualize thethree-dimensional imaging data in various formats (see the ComputerProgram Listing Appendix and discussion hereinafter). The formatsinclude orthogonal two dimensional images, oblique two-dimensionalimages, and translucent three-dimensional rendering. All of thesereconstructions can be directly displayed on the computer monitor; andthree-dimensional translucent, stereoscopic, rendering is also availablein the VR (Virtual Reality) mode.

One of the preferred ultrasound probe 12 for example, is a conventionalKretz ultrasound imaging system manufactured by Kretz Corporation, nowavailable as Medison Combison 530 through Medison America Corporation,Pleasantown, Calif. This system and other such conventional systems arereadily available and can provide real time ultrasound image data. TheMedison Combison ultrasound system incorporates an endorectal probewhich acquires multiple image planes in real time and in certainembodiments the software (see the Computer Program Listing Appendix)reconstructs the translucent three-dimensional volume. Another exampleis of a B&K Leopard ultrasound imaging system with endorectal imagingprobe (Boston, Mass.). Alternate systems include biplanartwo-dimensional imaging systems with the probe mounted in a steppermotor driven holder for rapid automatic acquisition of multiple imageplanes.

In a most preferred form of the invention, the system 10 includescomputer software for real-time image acquisition, image contouring,dose calculation and display software, dose volume histograms,three-dimensional dose contours, post-implant seed localization, and thepatient scheduling spreadsheet software. The Computer Program ListingAppendix of computer software shows how to implement thesefunctionalities. FIGS. 12A–M illustrates the operative connectionbetween modules of the software. The system software enables atwo-dimensional and three-dimensional image visualization forbrachytherapy employing two-dimensional ultrasound imaging for use inradioactive seed implants of the prostate. The software for thebrachytherapy seed implant and dose calculation system was developed ona Pentium-based processor with supporting graphics and digitizinghardware. The software consists of two-dimensional and three-dimensionalroutines. The two-dimensional tools consist of standard imaging toolslargely available for CT and MRI applications. These tools includedisplays of the imaging volume in any of the three standard orthogonalplanes (transverse, sagittal, and coronal), in addition to the abilityto display the imaging in any arbitrary, oblique imaging plane. Standardimage processing tools such as real time window leveling, zoom and panwill be available. The three-dimensional tools consist of athree-dimensional rendering of the actual contour slices imaging data.Based upon volumetric patient studies, the prostate volume can bedisplayed. The user has the option of viewing one or a mixture oftwo-dimensional and three-dimensional surface views on the monitor.

Contouring tools are also available for the user to draw with the mouseoutlines, or contours, of any structure visible on the imaging plane.Each contour can be varied as to color, line thickness, and line patternto aid in distinguishing between different contour sets.

Once a set of two-dimensional contours has been defined, either manuallyor automatically, on a number of different image slices they can bereconstructed in real time in the three-dimensional translucent view(described in more detail hereinafter). This results in a surfacerendering of the volume bounded by the contours. The surface renderingcan be chosen to be transparent, solid, or invisible (not rendered atall).

Once a seed has been placed into treatment position (details concerningseed implantation provided later), the user has the ability to displaythe dose of one or a set of seeds. The dose as a function of positionfor a cylindrical ¹²⁵ or ¹⁰³Pd seed of a given activity can bedetermined from a lookup table or calculated from an analytic formula.The dose field can be visualized as a set of isodose lines intwo-dimensions or isodose surface in three-dimensions. The process ofconstructing an isodose line or surface is defined by simply drawing apoint for each pixel/voxel which contains a certain specified dosevalue. For example, the user can specify that the 137 Gy, 120 Gy, 100Gy, and 60 Gy isodose lines be drawn on the two-dimensional slice foreach image plane, and the 137 Gy isodose surface shown on thethree-dimensional rendered mode. Again, similar to the contouredvolumes, the isodose surface can be reconstructed in any of the userselected modes defined for contoured volumes.

The features/capabilities of the system software functionalitiesinclude: complete patient database archive and dose plan “playback”;external image import capability; look-up tables for multiple seed kitsand template guides; multiple ultrasound imaging machine configurationcapability; image slice contouring using mouse, with edit capability;image cropping, image sizing, tiling, cascading; three-dimensionaldisplay of prostate, urethra, and other anatomies; rapid “on-line” dosecalculation in operating room/cysto suite during procedure; dose displaywith isodose lines, three-dimensional translucent, and ditheredisodoses; image export and printing (dose slices, contour slices, etc.);seed implant plan export and printing; dose volume histograms (withexport and printing); three-dimensional image support includingthree-dimensional image reconstruction from slices; three-dimensionaldisplay of isodose surfaces; image slice selection fromthree-dimensional image through any transverse plane; post-implantassessment including automatic seed localization; computer-controlledstepper; selection of manual (mouse entry), semi-automatic (buttonpush), or full automatic (computer-controlled stepper) ultrasound imagecollection.

For collecting ultrasound image data, the diagnostic transrectalultrasound probe 12 (see FIG. 2) is inserted into the patient's rectumto obtain real time volumetric images of the prostate for use during theimplant procedure. The diagnostic probe 12 is preferably a phased arrayprobe designed so that the array of transducers can rotate about theaxis of the array sweeping out a three-dimensional imaging volume. Asthe probe 12 rotates, images are captured and digitized by use of theimaging card 14 (see FIG. 1A), so as to create a fixed number of imagesslices per rotation. An alternative method utilizes a transverseoriented phased array form of the endorectal probe 12 which is movedlongitudinally in an automated rapid sequence so as to create a seriesof transverse image slices automatically. Another embodiment of theprobe 12 can incorporate multiple transverse phased arrays (shown inphantom in FIG. 1B) arranged parallel to each other orthogonal to theaxis of an endorectal probe to produce multiple simultaneous imageslices (see, for example, FIGS. 5A and 5B). The three-dimensional imagedata will be represented as a three dimensional image raster.

The ultrasound probe 12 can be mounted into a probe holder 40 (see FIGS.3A and 3C) with FIG. 3B illustrating one example of an ultrasound imagefrom an anatomical prostate phantom employed to carry out testing andplanning. The probe holder 40 includes a digital encoder 42 forproviding information regarding the position of all of the desiredultrasound image planes in the prostate relative to each other. Theimage plane location will be automatically sent to the system computerand “tagged” to the acquired ultrasound image for that position (FIG.2). Thus, it will be possible to reproduce the longitudinal and lateralpositions of the implant catheters for the ultrasound therapyapplicators and for the temperature probes.

A probe holder/stepper assembly 21 (see FIG. 1A and in particular FIGS.13A and B) accommodates most ultrasound endorectal probes from variousmanufacturers. A “collett” 23 surrounds the probe 12 and is insertedinto the stepper/probe holder assembly 21. The stepper 21 is a digitaldevice with an automatic imaging link to the ultrasound machine and tothe remainder of the system 10. The stepper 21 has three digitallyencoded axes: main probe stage longitudinal axis 31, needle insertiontemplate longitudinal axis 33, and the rotational axis 35 of the imagingprobe itself. The stepper 21 automatically records the longitudinal(z-axis) position and sends that information to the computer 16.Whenever the user desires to acquire an image plane, the spatialposition of that image plane is automatically registered with thatimage. Thus, it requires less than a minute to digitally acquire anddocument all the image planes in a typical volume study. The stepper 21can be incrementally moved by the user with stepper knob 34 and thetemplate 25 can be stepped by template positioning control 36.

The holder/stepper assembly 21 can move the probe 12 in 2.5 mmincrements. A transrectal probe from B&K was used which operates at afrequency of 7.5 MHz and contains two sets of 128 transducer elementsforming both transverse and sagittal imaging assays. The imaging probe12 was moved via a knob on the side of the stepper 21 and its positionmeasured via a digitally interfaced optical position encoder. The probeholder/stepper 21 with transrectal probe 12 mounted is shown in FIG. 1.The real time multi-plane ultrasound probe 12 was modeled by obtainingsingle digitized transverse images at either 2.5 or 5 mm intervalsthrough the ultrasound prostate imaging phantom. The ultrasound prostatephantom is available from Computerized Imaging Reference Systems Inc.and contains a model of a prostate, urethra, and seminal vesiclesimmersed in a gel filled plastic box. The box has a cylindrical hole inthe base for the insertion and positioning of the transrectal probe anda perineal membrane for performing practice brachytherapy implants.FIGS. 4A and 4B display a schematic of the brachytherapy phantom. Oncethe static image slices have been digitized they were then inputted tothe software in a continuous cycle to model actual real time acquisitionof a full volume. Multiple sets of image slices can be obtained andrandomly cycled to more accurately simulate the actual three-dimensionalreal time ultrasound probe 12. The image slices are input to thesoftware transparently.

A probe stabilization system 27 (see FIG. 13B) is designed for use withany standard probe holder/stepper 21, yet it is optimized for use aspart of the system 10. This stabilization system 27 attaches easily andquickly to the cysto or operating room table using clamps 28, yetprovides maximum flexibility during patient setup. The stabilizationsystem 27 provides for five degrees of freedom of motion, yet is robustand stable. The probe stabilization system 27 includes a stepper probestand control 44 which allows up and down movement. Further motioncontrol is provided by stabilizer control 29 which enables up and downmotion and left to right along rods 30 (horizontal) and rods 32(vertical). Gross motions are positively controlled in a stable manner.Fine motions are obtained with the same controls and are exactlyreproducible.

A variety of the templates 25 (see FIG. 2) for the needles 19 can beused with the system 10. All of these implant templates are disposablepreferably. The system 10 can also accommodate use of other standardtemplates 25. The system software (see the Computer Program ListingAppendix) can store the configuration of any number of the templates 25for immediate recall. Each template 25 stored in the system 10 isspatially registered with each ultrasound system configuration stored inthe system software.

The system templates 25 provide assurance of sterility for patientcontact at a cost similar to that of sterilization of the usual standardtemplates. The disposable system templates 25 are a fraction of the costof standard reusable templates and provide greater safety.

There are several possible image processing cards which could beutilized; however, using current modalities each of the processing cardsis configured specifically for three-dimensional. The three-dimensionalimage raster is buffered; and thus, for example, if the two-dimensionalimages are 512×512 and there are sixteen image planes in the probe 12,and each pixel is a byte (256 gray scales), at least a 512×512×16byte=4.2 Mbyte image buffer in the card 14 is needed. Several commercialcards (for example, made by Coreco, Matrox and Integral Technologies)can be equipped with this amount of video RAM (VRAM), but the way thecard's hardware interacts with the computer's video and software driversdoes not utilize this data in three-dimensional. Current availablemethodologies enable augmenting the software and some hardware of thesecards so that they can act as a three-dimensional card. The processingand memory architecture preferably is designed to allow for simultaneousimage acquisition and processing. The digitizing card should alsopreferably have standard imaging tools, such as real time window andleveling, zoom and pan of the ultrasound images. Some existing cards(e.g., Matrox; Coreco) do provide standard imaging tools.

The three-dimensional image data arising from the ultrasound probe 12 ispreferably buffered on the imaging card 14. The three-dimensional imageis preferably represented as a series of two-dimensional images. This isreferred to as the image stack or three-dimensional image raster. Thethree-dimensional image raster is represented in memory as a lineararray of bytes of length N×M×P where N is the width of thetwo-dimensional image in pixels, M is the height a two-dimensional imagein pixels, and P is the number of two-dimensional images in the imagestack.

In a preferred embodiment the user can include defined formats. Entirethree-dimensional image stacks at specific times during theintraoperative session can be stored in the DICOM standard. The userwill have the ability to select a three-dimensional image volume forarchiving as part of the system software. These image stacks can then bereviewed in any of the various visualization modes (standard orthogonaltwo-dimensional views, oblique two-dimensional views, orthree-dimensional translucent views) as described above. In addition,the user will have the ability to store any of the two-dimensional viewsavailable at any time during the intraoperative session.

The computational platform can, for example, be any form of computingmeans, such as the personal computer 16, which incorporates a PCI busarchitecture. Currently, PCI bus is preferable over the ISA or EISA busbecause the PCI bus is much faster. However, a generic system which willbe suitable for this applicable will be described. A 200 MHz (or greaterspeed) Pentium/Pentium-Pro computer supplied with 128 Mbytes of RAM anda 6.0 Gbyte hard disk should be sufficient RAM and disk memory to runthe software in a real-time fashion and to archive all patient data.There should be sufficient RAM to facilitate host image processing inparallel with onboard image processing for quality assurance checks. Ahigh resolution monitor capable of displaying at least 1280×1024×64 bitresolutions is preferably used.

Based on currently available technology, the ultrasound images obtainedfrom the ultrasound imaging system of the ultrasound probe 12 can be ofgood diagnostic quality. When transforming this input image data into athree-dimensional representation, whether in the three-dimensionalperspective mode or the real time VR mode, the resultant volumes can,however, be noisy and hinder diagnostic and spatial accuracy. In orderto improve the image quality, a number of conventional hardware andsoftware filters can be used which will filter the incoming image datastored on the imaging card 14. Routines such as image pixel averaging,smoothing, and interpolation can improve the three-dimensional renderingof the imaging volume. These sets of filters or routines are to bedistinguished from the set of standard imaging tools running on the hostCPU which are available within a conventional imaging software package.

In the preferred embodiment, three of the perspective views are thestandard transverse, coronal and sagittal two-dimensional views. Thesethree orthogonal views are taken from a user specified location withinthe imaging space. For example, the user can request that the threeorthogonal views have their common centers at a spatial position of (5.0cm, 15.0, 25.0 cm) relative to the origin of the template system. Onealso can select the reference point of either of the three orthogonalviews independently, that is the three views do not have to have commoncenter points. As mentioned hereinbefore, FIGS. 5A and 5B show examplesof several example two-dimensional views from a three-dimensionalultrasound image volume. FIG. 6 shows a number of possible viewingdirections, and FIGS. 7A and 7B give further examples of translucentthree-dimensional viewing from different angles. The three-dimensionalultrasound image volume was obtained from actual ultrasound images of ahuman prostate and of a prostate implant phantom.

On each of the views, one can define, draw and edit contours usingconventional computer software, such as Microsoft Foundation Class (MFC)view files. Each contour can be given a unique name by the user, andthen drawn by the user using the mouse of the computer 16. Allattributes of the contours such as name and color can, based onconventional imaging software, be user selectable. The user can alsoedit the contours by selecting functions, such as adding a point to acontour, deleting a point from a contour or deleting the entire contour.Once the contours are defined, the user has the option to render them inthree-dimensional or view in conventional two-dimensional mode on thethree-dimensional perspective mode or viewed in the VR mode. Again, allcontour three-dimensional attributes such as color, lighting, andshading are user controlled. The contours by default appear on thetwo-dimensional images, however, the user can control the individualcontour's two-dimensional and three-dimensional visibility.

In order to improve the ability to visualize the real time,three-dimensional information, the three-dimensional image raster can berendered as a real time, transparent, three-dimensional volume. Thistransparent volume can be viewed and displayed on the monitor of thecomputer 16 at any arbitrary viewing angle and is calculated usingconventional three-dimensional object reconstruction algorithms. Suchstandard algorithms can render a large imaging volume in fractions of asecond, even on present day computing platforms. The transparent natureof the reconstruction thus allows the user to “see” inside any objectswhich appear in the imaging volume. For example, if the prostate isimaged in the imaging volume, then it will be reconstructed as atransparent volume, in which other anatomical landmarks such as theurethra, tissue abnormalities or calcifications can be seen. Inaddition, if any other objects such as needles or catheters are insertedinto the prostate, and if they are visible in the ultrasound images,they will be seen as they enter the prostate (see FIG. 8 showingintroduction of the seed 18 with the catheter/needle 19). Since thevolumes are rendered as transparent solids, the needles 19 (and otherarticles) can thus easily be seen as they move inside the prostatevolume as well. Since the ultrasound images are obtained in real time,the three-dimensional perspective reconstruction is also rendered inreal time. The preferred algorithm for the perspective three-dimensionalreconstruction is the known Bresenham ray-trace algorithm.

As described above, in the routine process of brachytherapy planning,the patient undergoes an initial volumetric ultrasound scan using theprobe 12. This scan is done before the radiation therapy planning or theactual implant. During the radiation therapy planning, the idealpositions of the radioactive seeds 18 (see FIG. 1A) within the prostateare determined. This ideal seed distribution is optimized to deliver adose distribution within the prostate that will deliver all theradiation dose to the target volume only, while sparing the surroundinghealthy tissues such as the rectum and bladder. The optimal positions ofthe seeds 18 and the optimal position of the needles 19 are recorded forlater use in the operating room when the needles 19 are loaded into thepatient. The seeds 18 are then loaded into the needles 19, and thephysician then attempts to place the needles 19 inside the prostateusing a template 25 according to the treatment dose plan positions(again, see example in FIG. 8)

In the most preferred embodiment the seeds 18 are loaded through theneedles 19. A selection of different types of the seeds 18 (differentlevels of radioactivity) can be loaded through passageways, P, shown inFIG. 14. Optical sensors 90 and 91 are redundantly disposed adjacenteach of the passageways P with an associated microprocessor 93 and 94monitoring the number of the seeds 18 being instilled through the needle19. Radiation sensors 96 and 98 monitor the radiation activity of theseeds 18 being loaded into the needle 19. Spacers 100 are also instilledinto the needle 19 for separating the seeds 18 to achieve the desiredlevel of radiation activity and radiation contours. Optical sensors 92sense, redundantly as for the seeds 18, the passage of the spacers 100.Furthermore, optical sensors OPT4A and OPT4B, as shown in FIG. 14, arepositioned downstream from where the three passageways P merge to form asingle passageway. Thus, optical sensors OPT4A and OPT4B are positionedto sense redundantly the instillation of both seeds and spacers throughthe needle.

In a most preferred form of the invention, an automatic seed/needleloading method is implemented automatically loading implant needles 19with the radiation seeds 18 and spacers 100 based upon a pre-plan (doseplan) determined in the operating room (OR) . This method accommodatesthe spacers 100 and separate leaded-acrylic see-through “bins” for theseeds 18 of two different activity levels. Thus, the needles 19 can beauto-loaded based upon optimal dose plans requiring seeds of differentactivity levels. The automatic seed/needle loading method and systeminterfaces directly to the computer 16 and reads the dose planinformation using the software of the Computer Program Listing Appendix.A display on the auto-loader then displays to the operator each needlenumber, template coordinate location, and status of needle loading. Eachof the needles 19 are attached one at a time to the auto-loader assemblywith a standard luer lock. The auto-loader has a sensor at the needleattachment point which detects if the needle 19 is attached for loading.Each of the needles 19 are then loaded in accordance with the pre-plan.

The automatic seed/needle loading method and system is thereforecompletely double-redundant, as mentioned hereinbefore. It incorporatesthe use of two totally independent microprocessors 93 and 94 whichconstantly check each other. Both the microprocessors 93 and 94 are alsoin communication with the system computer 16. The seeds 18 and thespacers 100 are optically counted independently. Needle loading isoptically checked for total number of loaded items and, further, aradiation detector array scans each needles 19 to confirm that theseed/spacer loading radiation pattern matches the pre-plan. Thisautomatic method and system will do so in the operating room in minimaltime, without the risk of human error in the loading of needles. Theseed loading method will include a pair of redundant 8051microcontrollers (the microprocessors 93 and 94) which will beinterfaced to the dose-planning and implant system computer 16 via aserial port. This interface will read the dose pre-plan information fromthe computer 16, without the need for paper printouts and manualloading. That information will be transferred to a controller whichcontrols the loading of each needle 19. The requirements and designcriteria for the automatic seed-needle loading method and system aredescribed as follows: self-contained and capable of loading seeds andspacers; system will protect operator of system from radiation; dualredundant counting of seeds and spacers; dual redundant radiationdetectors for measuring radiation from active seeds versus spacers; dualredundant measurement of radiation seed positions in needles; systemcheck for failure of either or both redundant counting and measurementsystems; alarm to both operator and to dose-planning and implantcomputer system in the event of error; ongoing account of seed andspacer inventory; tracks needle loading configuration and displays tooperator the designated template grid hole coordinates for each needleloaded; sterilized cassettes for holding seeds and spacers, plussterilizable needle connector; includes one cassette for seeds and onecassette for spacers; dispenses one seed and one spacer at a time, andverifies optically and by radiation detector; system displays needlenumber and template grid location during loading procedure; automaticacquisition of needle loading plan from main system computer; serialinterface with handshake protocol and verification; self-contained(mechanical, power, logic, microcontrollers) ; operates only ifconnected to main system computer.

A convenient storage system for the needles 18 can be loaded by theautomatic seed/needle loading method system. The face of this unit has ahole grid pattern which matches the implant template 25. Loaded needlesmay be inserted into this unit until they are used. The entire unit isshielded for radiation leakage minimization. The template-like face ofthe unit is available in both a reusable, sterilizable version anddisposable versions which match all standard implant template faces.Faces of the unit detach easily and quickly for sterilization ordisposal.

The dose as a function of position for a cylindrical ¹²⁵I seed of agiven activity can be determined from a lookup table or calculated froma conventional analytic formula. The dose field can be visualized as aset of isodose lines in two-dimensional or isodose surface inthree-dimensional (see FIG. 9). The dose computation routine is basedupon the TG43 standard adopted by the AAPM (American Association ofPhysicists in Medicine) entitled “Dosimetry of InterstitialBrachytherapy Sources”: Recommendations of the AAPM Radiation TherapyCommittee Task Group No. 43 which specifies the dose model and the dataused in the dose calculation. This particular implementation runsextremely fast on a conventional 233 MHz PC, computing the dose for asingle seed in less than 0.5 seconds. The total three-dimensional dosedistribution within the prostate for a 100 seed implant requires only 50seconds, or less than one minute total computation time. Thus, this canbe done “on line” in the operating room.

In the two-dimensional, three-dimensional perspective, or the real timeVR modes, the user has the ability to view the optimized seeds 18 andthe needles 19 in the same volume as the real time ultrasound data. Thisallows the physician to see exactly where the needles 19 should go andhence make adjustments to position the needles 19 optimally. Thepre-planned, optimal positioned needles 19 and the seeds 18 can berendered again as a transparent solid, the color of which is userselectable. As the real needles 19 are inserted into the prostate, theirpositions relative to the ideal needle placements based on the dose plancan be monitored in real time. Any deviation of the position of a givenneedles 19 can be quickly and accurately readjusted so as to follow thepath of the ideal needles 19. As the different needles 19 are placed atdifferent positions inside the prostate, the viewing angle can beadjusted to facilitate viewing of the needle or catheter placement.FIGS. 5A and 5B displays perspective three-dimensional views and thethree orthogonal reconstructions of the image data along with thepre-planned catheter positions. The pre-planned needles 19 can also beviewed in the VR mode as virtual objects overlaid onto the imagingvolume.

A flowchart description of the translucent volume visualizationmethodology is shown in FIG. 10. The input image volume is described bythe vectors i, j, k of appropriate magnitude for the volume. The viewingangle parameters are the angles θ, Ø described on FIG. 6 and FIG. 10.The rotation matrix, R, is calculated using the formulae given in theflowchart of FIG. 10. The entire imaging volume is calculated bymultiplying the rotation matrices in the x, y, z directions by therespective vectors i, j and k describing the incremental portions alongthe x, y, z directions. Thus, the multiplying vector is (i—i_(o),j—j_(o), k—k_(o)) where i_(o), j_(o), k_(o) are the starting pointsalong x, y and z axes and the volume is determined by summing thecomponent contributions shown in FIG. 10. The three-dimensionaltranslucent image is then created by computing the translucenttwo-dimensional image over the entire image volume and summing thez-pixels.

A virtual reality interface system can be composed of a conventionalhead mounted display (HMD) 50 shown in FIG. 11 and a 6D (x,y,z, roll,pitch, yaw) tracking system. The HMD 50 consists of two color monitorswhich mount to a head set in the position directly in front of the eyes.The HMD 50 is based on the principal that whatever is displayed on eachmonitor is directly incident on the retina for each eye, and hence truethree-dimensional images can be created by rendering objects asthree-dimensional perspective images for each eye. Given the distancebetween the eyes (the interocular distance which is approximately 80 mm)and the distance and spherical angles of the distance of the center linebetween the eyes from the coordinate origin, the two-dimensional imageswhich appear in each of the two monitors can be determined exactly asdescribed above. This results in a true three-dimensional image asperceived by the user. Therefore, as the user moves his or her head ormoves around the room, the distance from the origin and the sphericalangles also change. This motion of the user or user's head can beobtained from the VR tracking system. Given these spatial parameters,the images which are reconstructed in the two eye monitors can beupdated in real time, giving the user the illusion of the object reallyexisting in three-dimensional space. The user literally has the abilityto walk around the object, viewing it in three-dimensional space.

Instead of reconstructing computer generated geometric objects as isusually the case in VR, the transparent, three-dimensionalreconstruction of the real time imaging data will preferably bereconstructed. Hence as the physician walks around the patientundergoing the implant, the physician will see the three-dimensionalultrasound volume mapped inside the patient's pelvis, spatiallycorrelated to the position of the patient's real prostate (or otherorgan) and anatomy. The physician can “see” inside the patient to theextent of what is visible in the ultrasound imaging volume. Since theultrasound probe 12 is locked down to the template, which is thensecured to the floor, the exact positions of all voxels in theultrasound imaging volume are known exactly relative to the template,and hence relative to the room.

As the needles 19 are inserted into the patient, they will appear in theimage volume and hence are reconstructed in the VR reconstruction. Allof this occurs in real time so that the physician also can see theneedles 19 enter the prostate in real time. As mentioned above, if thepre-planned, optimized needles 19 are displayed, the physician can thensee the position of the actual needles 19 as they are being insertedrelative to the optimal placement. Hence, the physician has the abilityto adjust the needles 19 to correspond to their optimal positions. Inaddition, since the needles 19 are automatically extracted, the computersoftware has the ability to calculate and render the three-dimensionaldose distribution in real time as the needles 19 are being inserted.

As an example, a currently available, a fast and inexpensive HMD is madeby Virtual-IO Corporation (Mountain View, Calif.). The HMD is full colorwith two 0.70 LCD displays with a resolution of 180,000 pixels per LCDpanel. The video input is NTSC with field sequential format. The LCDpanels are semitransparent, allowing the real outside world to beincluded in the virtual reconstruction. The field of view is 30° foreach eye. A six degree of freedom (6 DOF) tracking system can also beattached to the HMD. The 6 DOF tracking system allows for thedetermination of the spatial position of the user's head and the yaw,pitch, and roll of the head. The conventional head set weighs only 8ounces and comes with stereo sound. Stereo sound is an extremelyvaluable technology in the operating room. With this capability, thephysician has the ability to monitor the patient's heart rate andrespiration rate while performing the implant. Hence any fluctuation inthe patient's vital signs can be instantly accessed and acted thereon ifnecessary.

The radioactive seeds 18 are made of high density material such asstainless steel, and hence have a very bright response in the ultrasoundimages. Therefore, automatic seed detection in the ultrasound images canreadily be accomplished, for example, by a simple thresholding algorithmalong with the requirement that the resultant objects which are removedby threshold have a certain maximum size determined by the actual sizeof the seeds.

Near-real-time visualization will provide immediate feedback to thephysician during the implant process itself. There is a clear need forthe visualization being available during the implant process. The nearlyreal time visualization is of great importance to the effective use of atranslucent overlay of the ideal seed pre-plan (from the therapyplanning process) in the three-dimensional volume. The physician can“see” in nearly real time the relationship of the needles and seedsbeing implanted to the ideal pre-plan locations and quickly accommodateredirection required prior to leaving the radiation seeds. Further, theneed for this in three-dimensional representation is very important toovercome the greatest fundamental limitation in brachytherapy, which isknowing at the same time both the lateral placement and longitudinalplacement of needles and seeds relative to the target volume andpre-plan. This is a three-dimensional problem which has up until nowbeen addressed in two-dimensional in a stepwise fashion without theability to “see” the exact location of where you are in the target. Thisreal time three-dimensional visualization also would speed the implantprocess in the case of brachytherapy as well as make it more accurate.It would also speed other minimally invasive surgical procedures andlocalized tissue ablation procedures (for example, cryosurgery orlocalized selected ablation of diseased liver tissue or local removal ofbreast tissue). These procedures could be accomplished with real timevisualization inside the tissue being treated with greater accuracy inshorter time. This aspect would reduce operating room time and costs tothe patient and health care system.

While preferred embodiments of the inventions have been shown anddescribed, it will be clear to those skilled in the art that variouschanges and modifications can be made without departing from theinvention in its broader aspects as set forth in the claims providedhereinafter.

1. A system for monitoring loading of radiation into an insertion devicefor use in a radiation therapy treatment to determine whether thetreatment will be in agreement with a radiation therapy plan, the systemcomprising: at least one radioactive source for providing radiationtherapy to a treatment region of the patient; an insertion device, theinsertion device being configured to hold the at least one radioactivesource, the insertion device for insertion into the treatment region toprovide therapy to the treatment region of the patient via the at leastone radioactive source held thereby; a computer automated optical sensorthat is positioned to automatically sense loading of the at least oneradioactive source into the insertion device and generate optical sensoroutput data indicative thereof; a radiation sensor that is positioned tosense a radiation pattern of the at least one radioactive source loadedin the insertion device and generate radiation sensor output dataindicative thereof; and a processor in communication with the computerautomated optical sensor and the radiation sensor, the processor beingconfigured to (1) interface with an external device to receive datarepresentative of the radiation therapy plan, the plan data defining (a)a number of radioactive sources to be loaded into the insertion deviceand (b) a radiation pattern for the planned treatment, (2) process theoptical sensor output data to determine a quantity of radioactivesources that are currently present in the insertion device, (3) processthe radiation sensor output data to determine an actual radiationpattern emitted by the at least one radioactive source held by theinsertion device, and (4) compare the determined quantity and thedetermined actual radiation pattern with the plan data to therebydetermine whether the actual treatment agrees with the therapy plan. 2.The system as defined in claim 1 wherein the insertion device comprisesat least one selected from the group consisting of a needle and acatheter.
 3. The system as defined in claim 1 wherein a plurality ofradioactive sources are loaded into and held by the insertion device,the system further including: at least one spacer for placement adjacentat least some of the radioactive sources within the insertion device, afirst container for holding at least one of said plurality of theradioactive sources; a second container for holding the at least onespacer; and another computer automated optical sensor that is positionedto automatically sense loading of at least one spacer into the insertiondevice and generate another optical sensor output data indicativethereof; and wherein the radiation therapy plan further defines a numberof spacers to be loaded into the insertion device, and wherein theprocessor is further configured to process the another optical sensoroutput data to determine a quantity of spacers to be loaded into theinsertion device and compare the determined spacer quantity with theplan data to thereby determine whether the actual treatment agrees withthe therapy plan.
 4. The system of claim 3 wherein the plurality ofradioactive sources comprise radioactive sources of at least twodifferent levels of radioactivity.
 5. The system of claim 4 wherein thefirst container comprises at least a first bin and a second bin, eachbin for holding radioactive sources of different radioactivity levels.6. The system of claim 3 further comprising: a controller incommunication with the processor; and an auto-loader in communicationwith the controller, wherein the auto-loader is configured toautomatically load the radioactive sources and the at least one spacerinto the insertion device under command of the controller; and whereinthe controller is configured to receive plan data from the processor andprovide commands to the auto-loader to perform automatic loading of theradioactive sources and the at least one spacer in accordance with theplan data.
 7. The system as defined in claim 6 further comprising atemplate having a plurality of openings for receiving the insertiondevice during the treatment, each opening corresponding to a templatecoordinate location.
 8. The system of claim 7 wherein the therapy plancomprises a plurality of insertion devices to be placed into differenttemplate openings, the plan data further defining, for each of theinsertion devices, (1) a number of radioactive sources to be loaded intothat insertion device, (2) a number of spacers to be loaded into thatinsertion device, (3) a radiation pattern for that insertion device, and(4) a template coordinate location for that insertion device, andwherein the auto-loader is further configured to automatically load theradioactive sources and the at least one spacer into the plurality ofinsertion devices under command of the controller, and wherein theauto-loader further comprises a display, the display being configured todisplay to the user the template coordinate location that corresponds tothe insertion device being loaded and a status for loading eachinsertion device as the insertion devices are being loaded.
 9. Thesystem of claim 8 wherein the plan data further defines an identifierfor each insertion device, and wherein the auto-loader display isfurther configured to display to the user the identifier for theinsertion device as that insertion device is being loaded.
 10. Thesystem of claim 9 further comprising an alarm for notifying the user ifthe processor determines that the actual treatment does not agree withthe therapy plan.
 11. The system of claim 8 wherein the auto-loader isfurther configured to load radioactive sources and spacers into theinsertion devices one at a time.
 12. The system as defined in claim 1wherein the processor is further configured to compare the determinedquantity and the determined actual radiation pattern with the plan datato thereby determine whether the actual treatment agrees with thetherapy plan before the insertion device is actually inserted into thetreatment region of the patient.
 13. The system of claim 12 wherein theprocessor comprises a plurality of redundant microprocessors.
 14. Thesystem of claim 13 wherein the optical sensor comprises a plurality ofredundant optical sensors.
 15. The system of claim 14 wherein theradiation sensor comprises a plurality of redundant radiation sensors.16. The system of claim 13 wherein the radiation sensor comprises aplurality of redundant radiation sensors.
 17. The system of claim 12wherein the optical sensor comprises a plurality of redundant opticalsensors.
 18. The system of claim 12 wherein the radiation sensorcomprises a plurality of redundant radiation sensors.
 19. The system asdefined in claim 1 wherein a plurality of radioactive sources are loadedinto and held by the insertion device, the system further including: atleast one spacer for placement adjacent at least some of the radioactivesources within the insertion device; a first container for holding atleast one of said plurality of the radioactive sources; a secondcontainer for holding the at least one spacer; and wherein the opticalsensor is further configured to sense loading of the at least one spacerinto the insertion device, wherein the radiation therapy plan furtherdefines a number of spacers to be loaded into the insertion device, andwherein the processor is further configured to process the opticalsensor output data to determine a quantity of radioactive sources andspacers to be loaded into the insertion device and compare thedetermined quantity with the plan data to thereby determine whether theactual treatment agrees with the therapy plan.
 20. A method for loadinga plurality of radioactive sources into an insertion device inaccordance with a plan, the method comprising: reading data thatdescribes the plan, the plan data defining (1) a number of radioactivesources to be loaded into the insertion device and (2) a radiationpattern for the plan; loading a plurality of radioactive sources intothe insertion device; optically sensing the loading of the radioactivesources into the insertion device; detecting a radiation pattern emittedby the loaded insertion device; determining from the optically sensingstep a quantity of radioactive sources within the insertion device;comparing the determined radioactive source quantity and the detectedradiation pattern with the plan data to thereby determine whether theloaded insertion device is in accordance with the plan.
 21. The methodof claim 20 wherein the plan data further defines a number of spacers tobe loaded into the insertion device, the method further comprising:loading at least one spacer into the insertion device, the at least onespacer interspersed within the insertion device between radioactivesources; optically sensing the loading of the at least one spacer; anddetermining from the spacer optically sensing step a quantity of spacerswithin the insertion device; and wherein the comparing step furthercomprises comparing the determined spacer quantity with the plan data tothereby determine whether the loaded insertion device is in accordancewith the plan.
 22. The method of claim 21 wherein the loading of theradioactive sources and the at least one spacer is performedautomatically based on the plan data.
 23. The method of claim 22 whereinthe plan corresponds to a plurality of insertion devices being loadedwith radioactive sources and spacers, the method further comprisingperforming the aforementioned steps for each of the insertion devices.24. The method of claim 22 further comprising notifying a user via analarm if the comparing step determines that the loaded insertion deviceis not in agreement with the plan.
 25. The method of claim 22 whereinthe step of optically sensing loading of the radioactive sourcescomprises optically sensing loading of the radioactive sources via aplurality of redundant optical sensors.
 26. The method of claim 22wherein the step of detecting the radiation pattern comprises detectingthe radiation pattern via a plurality of redundant radiation sensors.27. The method of claim 22 further comprising performing theaforementioned steps in preparation for a prostate brachytherapyprocedure.
 28. The method of claim 22 further comprising performing theaforementioned steps in preparation for a tissue ablation procedure. 29.A loading system for preparation for therapy of a treatment region ofthe body of a patient in accordance with a therapy plan, the systemcomprising: a first container for holding a plurality of seeds fortreatment of the patient, each seed held by the first container emittinga first amount of radiation; a second container for holding a pluralityof seeds for treatment of the patient, each seed held by the secondcontainer emitting a second amount of radiation; a third container forholding a plurality of spacers; an insertion device for holding selectedones of the first container seeds, second container seeds, and spacers,the insertion device for insertion into the treatment region of thepatient to deliver therapy thereto; a processor configured to read datadescribing the plan, the plan data defining how selected ones of thefirst container seeds, second container seeds, and spacers to be loadedinto the insertion device; an auto-loader for automatically loadingselected ones of the first container seeds, second container seeds, andspacers into the insertion device in accordance with the plan data; aplurality of passageways leading from the auto-loader to the insertiondevice, each passageway corresponding with a different one of thecontainers, wherein the auto-loader is configured to automatically loadselected ones of the first container seeds, second container seeds, andspacers into the insertion device through the passageways; and aplurality of automated sensors positioned to automatically monitorpassage of first container seeds, second container seeds, and spacersinto the insertion device, thereby generating sensor output dataindicative thereof, wherein the plurality of automated sensors comprise(1) at least one automated sensor positioned to monitor passage of afirst container seed through the passageway corresponding to the firstcontainer, (2) at least one automated sensor positioned to monitorpassage of a second container seed through the passageway correspondingto the second container, (3) at least one automated sensor positioned tomonitor passage of a spacer through the passageway corresponding to thethird container, and (4) at least one automated sensor positioned tomonitor passage into the insertion device of all of the selected ones ofthe first container seeds, second container seeds, and spacers; andwherein the processor is in communication with the automated sensors andis further configured to (1) process the sensor output to determine aquantity of the selected ones of the first container seeds, secondcontainer seeds, and spacers that have been loaded into the insertiondevice, and (2) compare the determined quantity with the plan data tothereby determine whether the loaded insertion device complies with theplan.
 30. The system of claim 29 wherein the automated sensors compriseoptical sensors.
 31. The system of claim 30 wherein the plurality ofautomated optical sensors further comprise: a plurality of redundantautomated optical sensors positioned to monitor passage of a firstcontainer seed through the passageway corresponding to the firstcontainer; a plurality of redundant automated optical sensors positionedto monitor passage of a second container seed through the passagewaycorresponding to the second container; a plurality of redundantautomated optical sensors positioned to monitor passage of a spacerthrough the passageway corresponding to the third container; and aplurality of redundant automated optical sensors positioned to monitorpassage into the insertion device of all of the selected ones of thefirst container seeds, second container seeds, and spacers.
 32. Thesystem of claim 30 wherein the seeds comprise radioactive sources, thefirst container radioactive sources emitting a first level ofradioactivity, the second container radioactive source emitting a secondlevel of radioactivity, wherein the plan data further defines a level ofradiation activity and a radiation contour for the plan, the systemfurther comprising: at least one radiation sensor positioned to detect alevel of radiation activity and a radiation contour collectively emittedby the selected ones of the first container radioactive sources, secondcontainer radioactive sources, and spacers that have been loaded intothe insertion device; and wherein the processor is in communication withthe at least one radiation sensor and is further configured to comparethe detected radiation activity level and the detected radiation contourwith the plan data to thereby determine whether the loaded insertiondevice complies with the plan.
 33. The system of claim 32 wherein the atleast one radiation sensor comprises a plurality of redundant radiationsensors.